Disarm Traps

An aptitude in the area allows the Character to disable traps. One must be aware of the trap's existence (via the Spot Trap Skill, or the like) before one can attempt to disarm it. This skill also allows you to arm traps as well.

To get master training, you just have to prove yourself to McPherson. To do
that, accept the key that he gives you and then head down through the trap
door in his house. You’ll find yourself in a maze of sorts, and all you’ll
have to do is walk through all of the tunnels and then go back up the ladder
and talk to McPherson. The traps in the maze aren’t any worse than the traps
in the rest of the game, so you can simply bite the bullet and walk right
through them if you have a competent healer with you. Note: When McPherson
trains you he’ll also give you trapmaker spectacles (+2 dexterity, +2
perception) which are pretty nice.